Comment 89 for bug 286424

> I've noticed this doesn't happens when you upgrade form 9.04 to
> 9.10 but if you install 9.10 from scratch you will see the error

That's expected -- the problem here is that Ubuntu's **default** xorg.conf file file is missing a line.

If you're upgrading from 9.04 to 9.10, Ubuntu probably keeps your existing xorg.conf, and if that file is already fine, you won't see this bug.